Train describer and platform indicator



Oct. 13,` 1942.y

J. B. GRIFFITHS ETAL TRAIN DESCRIBER AND PLATFORM INDICATOR Filed June si'. 1 939 4 sheets-'sheet 1 [I ILlj Oct. 13, 1942 J. a. GRIFFlrI-ls ETAL 2,298,939

'I TRAIN DESCRIBER AND PLATFORM vINDICATOR Filled June 9, 1939 4 Sheets-Sheet 2 INVENTOR .z a. @mfr/ms Oct. 13, 1942- J. B. GRIFFm-ls Erm.

TRAIN DESCRIBER AND PLATFORM INDICATOR Filed June 9, 19259 4 Sheets--Shee'rI 3 l Rses Wwwkwk E,

ORNE Y 0f 13, 1942- J. B.`GR1FFrrHs ETA|.

TRAIN DESCRIBER AND PLATFORM INDICTOR' 4 Sheets-Sheet 4 Filed June 9, 1939 kat s@ m www INVENTOR J 3. AWF/77H5 A U 1' EY Patented Oct. 13, 1942 TRAIN DESGRQIBER AND PLATFORM INDICATOR John Balmain Grimm nest John Tervet,l

s, Andrew Brown, and-Er London, England, assgnors` tolnternational Standard Electric Corporation,

New York, N. Y.

Application June 9, 1939, Serial No. 278,380

In'Great Britain June 9, 1938 This invention relates to equipment for storing in succession pieces of informatiom'which will hereinafter be referred to for convenience as descriptions; such equipment being known in connection with train d'escribers and platform indicators used in railway systems.

In accordance with this invention a device for storing descriptions comprises a cylinder carrying a number of sets of radially movable code-pins,

the pins of a set being selectively actuated toY store a description.

In accordance with a further feature ofthe invention, a device for storing descriptions represented by a combination` of what may for lconvenience be denominated active and fpassive code-elements, for'example positive and negative electrical impulses, the total of code elementsA in a description being always the same, comprises storage-elements arranged in a plurality of similar sets, with one storage-element inthe set particular to each code-element in the code, each set being arranged to receive one description Lby the selectiveactuation of the st orage-elementsuin accordance with the descriptive combination, and to store the received descriptionk by a mechanical locking of the elements after actuation. y

One of the advantages of the inventionY is that by making the pins or storage-elements mechanically locking, stored descriptions will not belost by a momentary failure of power supply. vAnother advantage is that the number of descriptions stored can vary, in other words-the positioning of a detector device to read one or more of the descriptions stored can be independent of the positions of the sets of pins or elements.

In a railway train describer, one portion `of the code, for example the rst ve impulses, could referto the required destination, the reversal of the polarity of a selected combination of electrical impulses providing the necessary distinction between a relativelyy large number of 'destinations. Similarly, the second portion ofA theA code might also consist of five impulses, thereversing of selected combinations of which would give the necessary selection of non-stopping particulars. l n

Any line fault which occasioned thekloss of one or more vimpulses or the addition of stray impulses, would produce an error in the total number of impulses in the code: in the case `of platform signs, the receipt of a faulty code could be arranged to leave a blank space on the indicator, and in the case of signal cabin receivers, the receipt of a false code'could, if desired, provide an alarm for the receiving signalman. In cases where there is a number of receivers in parallel, a fault on one'receiver'will" not interfere with the transmission of a description Ato other receivers, but'under no-'circumstances will a faulty` code transmission display a wrong description, either to the public or to a succeeding signalman.

The indicator display may be carried out by a motor-driven rotary switch or sequence switch. rlhe use of sequence switches provides reliably spaced code impulses without reliance on'relay timing or ratchet driven mechanism, and in addition the contact'between sequence switch cams and 'brushes permits the use ofV relatively heavy contact pressures, the self-cleaningV action of the rotating cams providing excellentcontact surfaces.

A cancellation vfacility may be provided by means of whichaa cancel code can be transmitted to all receivers which Will delete both the destination 'and thenon-stop portions of the lastdescription received and permit a new description to be inserted in its place. This facility is valuable, since it is probable that a vsignalm'an having transmitted a description in error, will realize his error when he is about to setup the next description.

lIt should be noted thatthe use of combinations of a relatively small number of code impulses and storage pins, very considerably reducesthe size of thestorage unit. For example, descriptions consisting of a selection of twenty-ve destinations Aand fifteen codes kof non-stop particulars, couldjby this method, be transmitted and stored in a nine-element code as opposed to the forty which would be `required if veach destination and non-stop were allocated a unique impulse.

AWhen the -description reaches a display position, i. e. rst4 or second description stored,'the combination of code pins may be utilized to position two sequence switches. 'One of vthese switches hasV cams of the standard type cut to control the illumination of the desired destination on the -platformsign to signalmans indicator. The other sequence switch controlling the display of non-stop particulars, maybe equipped .with easily detachable selectorbars to provide a completely flexible selection of non-stopping particulars, together with theinterchange of receiver units between stations. These vselector bars take the form of metal inserts which can be supplied already sectionalized .soV that it is the work Yof a vfewminu'tes for a lineman to cut selector bars to correspond with the selection of nonstopping particulars required at Vany station and to insert the bars inpthe corresponding grooves in 2 the sequence switch. Thus it will be seen that when a sequence switch is driven to a pre-determined position in accordance with the code received, the cutting of the chosen selector bar will effect the display of the requisite non-stopping particulars.

In order that invention may be clearly understood, a description will be given of one embodiment, reference being made for this purpose to the accompanying drawings in which:

Figure 1 is a side view in section of a mechanical description storage device.

Figure 2 is a left-hand-end View;

Figure 3 is a right-hand-end View;

Figure 4 shows a circuit diagram of the receiving side of the equipment;

Figure 5 shows a circuit diagram of the indicator-change side;

Figure 6 shows in section the driving mecha-- nism of a sequence switch.

Mechanical storage unit The mechanical storage unit is shown in Figs. 1 to 3, and takes the form of a cylinder carrying a number of angularly-spaced parallel sets of radially-movable code pins, and a detector within the cylinder. A combination of pins of a set can be operated to store a code received, the operated code pins being mechanically locked in position until they have subsequently been detected to control the description displayed. The cylinder is moved round through one step, that is through the angular distance between two adjacent sets of pins, each time a description is to be received, and in so stepping takes the detector with it. The detector on the other hand moves one step in the opposite direction each time the display is to be changed, this stepping being effected either manually, or automatically in response to the operation of a track relay by the outgoing train.

The cylinder I is mounted on a horizontal axis, supported by bearing rollers 2 running in circumferential grooves 3 on the outside of the cylinder. At one end the cylinder I is formed with a sleeve portion I which constitutes a journal for a stub axle 2 xedly mounted on a drum 4, this drum being supported also in a bearing block 5 at its other end.

Within the drum 4 is housed an electric motor and its step-down gearing, the two being indicated in the drawings under reference motor II. The motor shaft 6 carries a pinion 1 and also off-normal cam discs 8 by means of which the motor II when once started up is caused to give one complete revolution to its shaft B and then come to a stop. The pinion 1 is in constant mesh with a gear 9 rotatably mounted on a shaft extending through a bearing in the end wall of the drum 4, and to this shaft is secured a pinion I0 meshing with a gear II fixed on the sleeve I of the cylinder I. The gear-combinations 1 9, and Ili-I I, each have a step-down ratio of l-to-6, so that when the motor II is set into motion to give one complete revolution of the shaft 6 there occurs a relative movement between the drum 4 and the cylinder I of one-thirty-siXth of a revolution, or ten degrees.

'I'he sleeve at the end of the cylinder also carries nxedly a worm-wheel I2 meshing with a worm I3 which is xed on a shaft I4 driven from a motor I through a step-down gearing, and, by the provision of the off-normal cams I5, Fig. 5, referred to below, made to execute one complete revolution whenever the motor I is started up.

H each set corresponding to f the bar to the left until the pins 'the end of the latching bar E ends of the The gear-ratio between the worm I3 and wormwheel I2 is one-to-thirty-six; hence whenever the motor I is started up the cylinder I is stepped round through ten degrees, and, assuming that the motor I1 is not then running, the drum 4 is carried with it.

The code-pins I6 are arranged in sets of ten` a train-description and being arranged in a straight line parallel with the cylinder axis with the individual pins passing radially through the cylinder Wall. The sets are spaced from one another by an angular distance of ten degrees so that there are thirty-six sets in all. Each pin I6 is urged outwardly by means of a spring I1, and is stopped by means of a shoulder on a conical portion I8 of the pin itself. Beneath each set of pins and running the whole length of the cylinder is a latching bar I9 which is constantly urged towards the right by means of a spring 20. Key-hole slots 2I in this bar allow the conical heads I8 of the pins to pass through only when the bar is in its leftward position. The action of depressing any one pin, or any two or more pins simultaneously, forces are fully depressed, when the bar springs back to the right again and the pins are retained in the operated position.

For operating that set of pins which at any moment is in the description-receiving position, shown at A' in Fig. 2, there is provided a set of ten strikers 22 each of which is operated when its associated magnet MA, MB, MJ is energised, and in operating strikes the underlying pin I6 to press it inwardly until it latches. Also, for the purpose of releasing all the latched pins of the set last operated, this in response to a special cancel signal, there is provided a cancel striker 24 and operating magnet MCL adjacent For releasing the pins of an obsolete description before the cylinder has gone full circle, a fixed ramp 26, Fig. 3, is provided just in advance of the description-receivingl position to engage the bars I9. This is necessary where two or more descriptions can be read simultaneously as will be understood from what follows.

The detector device is arranged inside the cylinder and comprises a beam 21, Fig. 1, which is supported at one end by a spider 28 riding on the interior of the cylinder, and at the other end by its slotted engagement with the stub axle 2 already referred to which projects from the drum 4. The detector can thus be removed and inserted Very easily once the holding ring 29 on the end of the cylinder has been removed. Fixed on the beam 21 is a series of spring-contacts 30, each contact being disposed beneath one of the pins I6 so that it Will be operated when that pin is depressed. This series reads the train description of the first train due; similar series for later trains may also be provided, and Fig. 2 shows a series 3I spaced ten degrees behind the first.

The functioning of the apparatus is as follows:

Let it be assumed that a description has just been set up, the circuit for doing so being described further on. This description will be stored on the set of pins indicated at A in Fig. 2, certain of which have been depressed and held by the latch bar I9. This set A' will remain in the description-receiving position as shown until the next description is about to be received, so that at any time up till then the operator at the distant transmitter can cancel the description transmitted should he nd that he has made a mistake. Of course it would be possible to have the cancel mechanism 24 set back one step, and to have the stepping of the cylinder follow immediately upon setting-up; but such an arrangement would deprive the transmitting signal-man of the opportunity of sending a new train description, for storage in that same set, after the first has been cancelled.

Now let it be supposed that a second train description is about to be received. The circuit arrangements for receiving the description will b e discussed in detail with respect to Fig. 4; it is suiiicient for present purposes to say that the first action is the starting up of motor I. The motor I causes shaft I4 to execute one complete rotation, stepping the cylinder I round through ten degrees in an anti-clockwise direction as seen in Fig. 2. If the motor II is inoperative at this time, the drum 4 will move in unison with the cylinder, and will carry with it the detector mechanism 21--30-3L Thus the contacts 36 will continue in engagement with the pin-set A in the new position, formerly occupied by set Z', ten degrees to the left of the vertical, and the pin-set B together with the contacts 3| will be in description-receiving position. When the complete description has been received on the appropriate relays and has been found satisfactory, certain of the magnets MA, MB, etc., selected according to the code, will be operated simultaneously, depressing the corresponding pins I6, these latching. The contact set 3| will then be selectively operated, to give a display or transmission of the description pertaining to the second train due.

Should the operator at the distant transmitter theniind that he has made an error, he can send the special cancel signal, which will energise magnet MCL to operate striker 24 and release the hold of bar I9 on the pins. This will not only itself cause no stepping of the cylinder, but will prevent, by circuit arrangements described below, such a stepping before the next description is sent, so that the pin-set B remains in position to receive such fresh description.

Now let it be assumed that the train A has passed out from the station so that the description has to be removed from the indicator board and the train-description B has to be brought into the position Next train due. Either manually or automatically the motor II is set into peration, giving one complete rotation to the shaft 6; This causes the drum 4 and the associated detector mechanism to rotate through ten degrees in the clockwise direction of Fig. 2, bringing contacts into engagement with pin-set B', and contacts 3| with pin-set C.

This condition, namely one description only in storewith a detector mechanism capable of reading two descriptions, shows the need for the fixed ramp 26, since in its absence the contacts 3| intended to read Second train due would be reading the obsolete description of the thirtysixth earlier train. However, the arrangement may be such that the description is not displayed when it is in the receiving position but only after it has been stepped away, this would have the advantage of preventing displays from being given while they are still open to cancellation, but would not be satisfactory where there might be only one train at a time in the system.

It-will be appreciated that although for eX- planatory purposes the motors I and II have been regarded as running only one at a time, in fact it is quite possible for both to be running together, motor I turning both cylinder and detector anti-clockwise, and motor II turning the detector clockwise with respect to the cylinder, so that its movement in space is neutralised.

It will also be noted that the extent of movement of the detector is never more than one complete revolution; as a consequence of this the leads from the contacts 30 and 3| can be of a simple kind, there is no necessity for brushes and like equipment necessary with continuously rotating members.

Incoming circuit arrangement The operation of the mechanical equipment just described is dependent upon the use of a suitable oircuit arrangement, and such an arrangement will now be described with reference to Fig. 4.

`In this circuit and also in the circuit of Fig. 5 the relays are designated by capital letters, the relay tongues are numbered consecutively and are designated in the specification by lower case letters corresponding to the reference characters indicating the particular relay and a numeral indicating the tongue member.

The signals from the distant transmitter come in over the pair of wires LI, L2, and consist of a constant number of impulses, thirteen in this case, made up of a long preliminary pulse, ten code impulses, a twelfth impulse, and a long iinal pulse. The preliminary pulse is for preparatory or starting purposes and is always negative; the ten code impulses may be negative or positive, the train-descriptive information being conveyed by the combination of negative and positive impulses; the twelfth impulse is negative during ordinary descriptive transmissions, but is reversed in polarity for the purpose of cancelling the last description set up; while the final long pulse, always negative, causes actuation of the strikers 22 (Fig. 2) of which the magnets are also shown at MA, MB, etc. in Fig. 4.

Every impulse, positive or negative, energises J the relay IR, but only the reversed or positive impulses energise relay IP also. The rst long pulse, the ten code impulses, and the cancel impulse energise in succession the twelve relays CA, CB, CL; and of these the first eleven prepare successively the circuits for the eleven relays AA, AB, AK, so that these will be operated if the next impulse is positive. A received impulse train consisting of the correct number of impulses will, at the end of the first twelve impulses, leave relay CL operated and relay CM unoperated, thus allowing operation of slow to release relay OK on the thirteenth pulse, to cause firstly energisation of the stepping relay SR and secondly energisation of striker relay TR. lIf too few impulses have been received, so that CL is unoperated, or too many, so that CM is operated, the fault relay NG is operated to move the drum a step, but no striking of the pins. The cancel signal, given by a reversal of the polarity of the twelfth impulse, operates the relay AK which is one of the series AA, AB, etc.

Considering this circuit now in detail, when the first long pulse is received, this pulse always being negative, relays IR, slow-to-release relay RG and RGA are successively operated by closure of contacts irI and rgI respectively and relay RGA applies at its contacts rgaI general battery feed AP to the system.

Thiscauses slow-to-release relay DC tc ener- V2,52%,.939 ingfcircuits-to :reIaysfOKand SR, releasing these rgiven,'ascould data 'concerning other tra-insafter '-relays, Jandopening at #srl-the loc-king circuit of `SRAfwhich releasesand opens it contacts sra2 releasing relay TR. Thus the receivingcircuit will be--restored to normal to await the ltranslm'issionfof the Anext train description.

As. already-described, a train description that has been set up -is not lstepped onward until vthis is necessary for the reception ofa further description. If now the transmitting signalman 'desires vto cancel the lasty description set up, he

sends the cancel signal, which consists as'before of along pulse, eleven short impulses, and a long nal pulse, all being negative'ex'cept the last short impulse. The operation of the relays CA, CB, CL will be as-already described, but of the relays AA, AB, AK, only AK will be operated, preparing the circuit at alcZ for the cancel magnet MCL. At alc3 the operating circuit to the relay SR. is broken, and the yiinal long pulse is passed direct to the striker relay TR, causing cancellation without previous stepping. The circuit may be tracedas follows: From negative potential trZ, olcS, alcZ, cancel magnet MCL tov ground. In addition the relay `AKA is operated, by a circuit from positive potential alcll, o-7c5, winding AKA to' ground. The operation of AKA breaks the circuit at a7ca2 via tr to stepping relay SR, thus preventing the operation of this relay and motor I to avoid the appearance of blanks on the indicator and the impulse, instead, at front contact alca2 goes to va winding of TR, which operates, and locks in,

and releases by the circuits described above.

`Once operated, AKA locks in by a circuit from positive potential, tongue and back contact tr, tical front contact, winding AKA to ground. AKA remains locked up until TR is operate-:l in the subsequent train description.

Faulty code If a code is received which consists of too few impulses, so that CL is inoperative, or `too many, so that CM is operated, the long nal pulse is transferred from the OK relayy to the NG relay at cm2. YThe'relays SR andfTR then operate in the `way already described, but the operation of relay m fails to cause the striker magnets MA, MB, .'to operate owing to'the fact that contacts okt are open which cuts ofi. the operating battery from tr2.

Detector circuit arrangement Reference will now be madeto F-igj5 for a description' of theY circuit associated with theV detector part of Figs.` 1-3 and including the display indicators.

The ten code-elements, stored by means fof the ten pins constituting a set,"are divided into two groups of live each, one 'group for describing the train-destination, and the othergr'oupffor the non-stop stations.

The ve wipers 3i] (Fig. 2) which give the destination description are associatedv with a rst sequence switch ISS (Fig. 5), while the lve wipers concerned with the non-stop data are associated with a second sequence switch ZSS. A third sequence switch SSS is used for the destination description of the second train due, i. e. in association with'the rst iive wipers of the second contact set 3| (Fig. 2). It has not been thought necessary for purposes of description to provide for this second train due, a nonstop indication, but of course this could easily be will be three-quarters.

the' second.

The sequence switchesSS, `ofwhich the l'me chanical details will become vapparent fromthe descriptionof Fig. G-below, are of a well-known kind, having a single-shaft carrying ve cam discs A, B, C, Dvand E. Such sequence'switches are well-known in the automatic telephone and railway signalling arts, Vand their various arrangements for cam and ContactA circuits! are well known, and since the structural details of-the sequence switches form `no part of the-present inventiomthey will only be referred to briefly, for'the purposes of explanation. I n'eachsequenceswitch three cams B, C and-'Dware-Kassociated with the wipers terminating the leads from the contacts 3i) shown diagrammatically in Fig. 5 and are cut so that an electrical circuit is established -for certain positions of the shaft; the

right-hand wiper of cam D is lconstantlyinengagement, and leads to-a drive relay-DR which so long as it is energised causes the sequence switch shaft to'rotate. Thus ifone of 'th'ecams say cam-B, is cut so that on its left-hand side it makes circuit during the rst halt-revolutionof the switch shaft, and on its right-handjside makes circuit during the firstand third quarters, then the following possibilities vexist for setting the switch: if pin No. 2A is down the switch shaft will advance through one-quarter revolution; if pin No. 1A is down the advancement will be through one-half; and with both pins down it This principle can be eX- tended to the other cams so that with a switch as shown thirty-one angular positions of the shaft are provided for, apart from the home position. The cam disc E is one Awhich makes contact in all positions other than the home position and thus serves to return the switch tornormal when the homing relay contacts hr2 are changed over. The cam disc A is for the purpose of setting the switch ac-curately` and precisely in the position-to which it is displayed by the depressionoi` a certain combination of pins I6. The operation of Ya sequence-switch driving-relay IDR, 2DR, etc. closes at Idri, Zdrl, etc. a circuit for the corresponding magnetic clutch, ISS/C, ZSS/C, etc. and for the motor-start relay MS. The main motor Fig. 5, common to all'the sequence switches, is made to run so long as any of the DRrelays are operated, and is clutched to any of the sequence switch shafts so longr as the corresponding Aclutch magnet C is energised. Contacts Idrl, Z'drl, 3dr! are fed from a source V.of positive potential and back contact of relay PR'the winding of which is connected through a rectifier across the leads from an alternating current source which operates a series of selectable lamps. The contacts of a circuit breaker CB'are in series vwith the source of alternating current and relay PR. When CB is energized by a circuit from, positive potential, backcontacts 3dr2, `2oZr2, |dr2, winding CB to ground the circuit lbreaker contacts are closed, the selected lamps are illuminateda'nd relay PR is operated holding its tongue away from its :back contact, thus opening the battery circuit to thewipers of cams A and the respective contacts ldrl, 2dri, ttrl, preventing the operation of the corresponding clutches. This arrangement serves to prevent illuminationr ofthe display board while the sequence vswitches are in'motion.

It will be understood that thirty-one permutations are possible with each of the three groups of five pins, and with the cam arrangement described, any of the sequence switches may be rotated selectively to any of thirty-one positions. lIn accordance with well known practice, rotary (contact members other than those above described may be provided which engage either singly or in combination with stationary con- 'tacts, provided according to circuit requirements' :in the various positions of the switches.

The circuit arrangement now about to be de- :scribed shows one form of an indicating arrangeiment.

The illumination of the appropriate lamps on :an indicator is given by a further set of cams F =on the shaft of the sequence switch. A circuit is established through any one of their wipers at- :any one setting of the switch and causes one of :the lamps L to be lit up.

As regards switches ISS and SSS, these cams Aare cut the same for all stations since all stations `will need to give the same display in response to Vthe same incoming code: but with the non-stop :indicator associated with sequence switch ZSS this will not be so, the meaning of a received code indicating non-stop will be different from station to station, consequently the cams F of switch I are replaced by code bars in switch 2 having contacts suiting the requirements of the respective stations.

The circuit shown in Fig. 5 includes means for automatically changing the setting of the indil cator boards when the rst train due has come and gone. The passage of the train away from the station or signal box causes the contacts of a track relay to close, energising the homing relay HR, which locks over hraZ. At hr2, hr3 and. hr4, circuits are closed for relays IDR, 2DR, 3DR, to restore the three sequence switches to normal, whilst at M5 feed is supplied through the contact of off-normal cam of to the motor II, so that this motor will start up, and being started will give: one complete revolution to its shaft 6. This results, as already described with reference to Figs. l to 3, in a stepping round of the detector mechanism. in the clockwise direction of Fig. 2. Just before the end of the prescribed one revolution, the cam closes a circuit to the relay HRA, which opens the normal locking circuit to relay HR at km2. Accordingly, when all three switches SS have reached their home positions, the circuits over cams E to the `driving relays DR will be r opened, releasing relay DR, then HR, and HRA. By this time the contacts 3i] and 3| will each be engaged by a fresh set of pins I6, and when the contacts hr2, hr3, hr4 again make to the cams B, C and D, the sequence switches will be started a up again, from their home positions as is essential, to give a new display.

Sequence switch mechanism Figure 6 shows the general construction of a sequence switch driving mechanism.

The shaft 5| of the sequence switch has at one end a gear 52 which is flexible, and which, when allowed to assume its normal, planar condition engages with a crown-wheel 53 on the shaft 54 of the main motor shown in Fig. 5.

When the sequence switch is at rest the flexible gear is warped under the pressure of a spring (not shown) acting upon an armature 55 carrying a rubber buer 55 which co-operates with a similar iixed buffer 51 to brake the movement of the switch shaft, stopping it immediately the clutch has been released. The iiexible gear 52 is freed, to clutch the switch shaft 5I to the driving shaft 54, when the clutch magnet'C is energized.

Fixed on the switch shaft 5I are the five cam discs A, E; each consisting of an insulating carrier 59 and a pair of conducting facings 60 each pair being permanently connected together, as by conducting rivets passing through the carrer. Inaddition the adjacent facings of the cams B, C and D are extended inwards to engage spacing bushes 6l, so that the six facings are in permanent connection `with one another.

The remainder of the selecting cams F on shaft 5l cooperate with stationary contacts in the usual manner, or an alternative arrangement may be 'used `in which radially placed code bars 62, Figures 5 and v6, may be used, having projecting teeth which when the bar assembly is rotated engage stationary contact members, according to well .known practice and thereby close selected circuits. This latter arrangement makes substitutions in existing display circuits easy, because the display bars may be changed readily. With this arrangement, when any one bar is brought into :reading position by the displacement of the se- .;quence switch it engages with a set of contacts GI, Fig. 5, which are selectively operated accordling to their meeting a tooth or a gap, thus causing the appropriate indication to be displayed.

What is claimed is:

A system responsive to received code signals wherein each code signal comprises a first long impulse followed in succession by a pluralityT of code impulses and a cancel impulse, a group of relay.; arranged to be operated in succession by said first impulse and said code impulses, a r0- tary drum, a plurality of axially disposed rows of displaceable pins on said drum, the pins in each row corresponding in number to the number of code impulses of each signal, a second group of relays arranged to be energized onl7 on receipt of code impulses of a predetermined polarity over circuits prepared by the operation of the rst group of relays, a plurality of striker magnets each controlled by a circuit prepared by the operation of a relay of said second group of relays, armatures for said striking magnets having a striking part, said striking parts each being disposed over a pin in one of the rows on said drum whereby actuation of a striker will displace the corresponding pin, a detector comprising a row of contacts disposed on a rotary support inside of said drum, indicator control circuits operated by said contacts, means for advancing said support a step at a time in reference to said drum so that the contacts thereon will be operated when brought into engagement with the displaced pins of a row, means responsive to a code signal to advance said drum a step so that a new row of pins is positioned under said strikers to be displaced according to the code impulses of said signal, a common locking means for each row of pins on a drum, means responsive to a special code signal including a cancel impulse for tripping said locking means and thereby releasing the set of pins last actuated, and means responsive to said special code signal for preventing the operation of said means to advance said drum.

JOHN BALMAIN GRIFFITHS. ANDREW BROWN. ERNEST JOHN TERVET. 

